Mobile communication systems are extensively constructed to provide various types of communication. For example, a voice and/or data may be provided through the mobile communication systems. The typical mobile communication system or network may provide access to one or more shared resources to a plurality of users.
In general, a multiple-access in the mobile communication system refers to a method in which a plurality of transmitters transmit signals within the same area having a limited frequency band by using the same transmission medium and share transmission capacity of the transmission medium through the multiple-access. The multiple-access technology is largely classified into two methods.
A first method corresponds to a contention-based multiple-access. A plurality of transmitters transmit multiple-access signals by using the same channel. At this time, when two or more signals are simultaneously transmitted, the signals may collide with each other. In order to solve the problem due to the collision between signals, a collision detection and recovery method, a collision avoidance method, or the like is used.
A second method corresponds to a channel resource division method. The transmitters exclusively receive a part of given channel resources and transmit multiple-access signals. At this time, the channel resource may be time, frequencies, orthogonal codes, or the like. The channel resource division method corresponds to a method in which a plurality of transmitters share all given resources, and an Orthogonal Frequency Division Multiple-Access (OFDMA) having an excellent frequency efficiency is mainly used recently.